It is increasingly the case that processors are being purpose built to fulfil the requirements of particular applications. The present invention concerns particularly, but not exclusively, a processor architecture for use in image processing or other multi-media applications.
Existing processor architectures use differing combinations of so-called scalar units and vector units. In the following, a scalar unit implies a unit capable of executing instructions defining a single operand set, that is, typically operating on a pair of source values and generating a destination value for each instruction. A vector unit operates in parallel on a plurality of value pairs to generate a plurality of results. These are often provided in the form of packed operands, that is two packed operands provide a plurality of value pairs, one from each operand in respective lanes.
Existing processor architectures use a scalar processor unit for multi-media processing. However, because there is little or no parallelism in this approach, the processor has to run very quickly. Even if the processor is capable of running quickly, it will be inefficient in terms of power consumption.
Other approaches have considered the coupling of a scalar processor with a vector processing unit. However, it is difficult to establish an architecture in which the advantages of the scalar unit and the vector processing unit can be maximised without placing restrictions on the processor operation. For example, if the vector unit is a separate processor it is difficult to achieve sufficiently tight integration to enable the scalar unit and the vector unit to work efficiently together. Alternatively, if the vector unit is part of the same processor as the scalar unit, it is difficult to construct a unit with sufficient parallelism but which can communicate intelligently enough with the scalar unit. It is also difficult for the scalar unit to keep the vector unit fed with enough data to achieve significant performance gains.
It is an aim of the present invention to overcome or at least mitigate such problems.